Composite materials, particularly those of fibrous type having a ceramic matrix, have recognised qualities, particularly their resistance to high temperatures and the gain in mass they bring about. However, in some applications, their use is restricted because of certain defects in their surface characteristics. There is an evident need to improve these characteristics, particularly in regard to the resistance of the materials to wear due to friction or erosion, their resistance to oxidation or corrosion, or to improve their surface condition, particularly their surface roughness. In certain applications, these deficiencies become apparent, bringing about decohesion of the fibres, particularly at the edges of the parts.
Some tentative solutions have been proposed, such as deposition by flame spraying or arc plasma. However, the adoption of these techniques often meets with difficulties due to inadequate adhesion of the resulting depositions. The keying quality obtained is inadequate, and the stresses caused by differential expansion lead to fibre decohesion.
Various coating processes, particularly in the case where resistance to erosion and corrosion of parts subjected to high temperatures is sought, have also been envisaged in FR-A-2 329 402, particularly the application of a protective coating to a substrate formed by a multi-layer metallic mesh brazed on the core of the part.